Hydraulic tripping mechanism



March 31, 1942. O T EB 2,278,310

HYDRAULIC TRIPPING MECHANISM Filed May 13, 1941 WITNESSES:

INVENTOR WJKWM 2 Mnmggs GOTTLIEB. 5. WWW

. ATTORNEY Patented Mar. 31, 1942 HYDRAULIC TRIPPIN G MECHANISM ManiousGottlieb, Philadelphia, Pa., assignor to Westinghouse Electric &Manufacturing Company, East Pittsburgh, Pa., a corporation ofPennsylvania,

Application May 13, 1941, Serial No. 393,200

6 Claims.

The invention relates to hydraulic mechanism for moving a suitableelement and it has for an object to provide apparatus of this characterwherein the mechanism shall include a piston arrangement responsive todecline in fluid pressure to effect movement of the element andresponsive to increase in fluid pressure after operation due to pressuredecline to reset the mechamsm.

A further object of the invention is to provide an element, such as atrip lever, which is moved by means of a rod having associated therewithouter and inner pistons biased by means of springs to move in onedirection against the force of fluid pressure, the arrangement beingsuch that, upon decline in fluid pressure to a predetermined extent, thepistons move to effect movement ofthe element, and such that, withrestoration or increase in fluid pressure to a predetermined extent, thepistons are returned to normal position.

A further object of the invention is to provide a device which isresponsive to decline in oil pressure to a predetermined extent tooperate a trip lever for bringing a suitable machine to a stop, themechanism being so constructed and arranged that, when the oil pressurethereafter builds up to a predetermined extent it is reset;

the mechanism including a piston arrangement subject to oil pressure andsprings which exert the necessary force, in the event of sufiicient dropin oil pressure, to cause movement of the mechanism to effect trippingof the lever or its equivalent.

These and other objects are effected by the invention as will beapparent from the following description and claims taken in accordancewith the accompanying drawing, forming a part of this application, inwhich:

The figure is a longitudinal sectional view of ably the conventionallever moved in response to decline in oil pressure to bring aboutstoppage of a suitable machine, such as, an elastic-fluid turbine.

The mechanism, at l, includes a cylinder 3 head I5 and the boreextending from the radial abutment face toward the first head l4.

An outer annular piston 20 fits the bore l6, it has an annular conicalvalve seat 2| disposed adjacent to its inner periphery, and it has aradial flange 22 disposed in the bore H, the flange having a radial face23 for cooperation with the radial abutment face I8, as will behereinafter pointed out.

An inner piston 24 has a peripheral edge 25 providing a valve member forcooperation with the annular valve seat 2|.

Preferably, the first cylinder head I 4 has a sleeve 26 extendinginwardly therefrom into the cylinder, the sleeve having a bore 21providing a guide for the rod I2 and having its external surface 28providing a guide-way for the inner piston 24, the latter preferablyhaving a hub or tubular extension 29 in telescopic relation with respectto the sleeve or tubular member 26.

The rod |2 has its inner end 3| disposed a substantial distance withinthe cylinder from the inner or abutment end 32 of the sleeve or tubularmember 26 and the inner piston is connected to the inner end 3| of therod. As shown, the inner piston has a sleeve or hub portion 33 extendingfrom the side thereof opposite to the hub or sleeve 29 and it has aninwardly-extending radial flange 34 providing a bore 35 for reception ofthe inner end portion 3| of the rod. The rod has a shoulder 36 engagingone side of the flange and the other side of the latter is engaged by anut 31 carried by the rod. Thus, the inner piston is positivelyconnected to the rod so that the two move together.

A first or outer helical spring 38 has one end engaging the springshoulder 39 formed on the outer piston 20 and its other end engaging thespring seat 40. Within the spring 38, there is arranged a second orinner helical spring 4| having one end engaging the inner piston 24 andits other end engaging the seat 40. The spring seat 40 is disposedadjacent to the second cylinder head I5 and it is adjustable axially ofthe cylinder by means of the stem 42 having threaded engagement withrespect to the cylinder head I5 From the structure so far described, itwill be seen that the outer and inner pistons 20 and 24 normally dividethe interior space of the cylinder into a fluid pressure chamber 43 andinto a spring space 44. The cylinder is provided with a fluid pressurepassage 45 for communication with any suitable source of oil pressure,and it has one end 46 in open communication with the interior of thespace or chamber 43. Thus, it will be seen that fluid pressure suppliedto the chamber 43 is applied to the piston areas of the outer and innerpistons 20 and 2d and facing toward the first piston head it, the.forces of fluid pressure so applied to the pistons being opposed by theforces acting in the other direction and due to the springs 38 and 4H.

The outer and inner springs 38 and 4| have different scales, the innerspring having the larger scale. For example, the scales may be suchthat, for the piston areas and from the po-- sition of the pistons shownon the drawing, the inner piston 24 will start to move toward thecylinder head M when the fluid pressure in the space 43 is at 3 poundsper square inch while the piston 20 will start to move in the samedirection when the pressure is at 2 /2 pounds per square inch. On theother hand, assuming that the pistons have moved inwardly toward thecylinder head I 3 with reduction in forces of the springs, then movementof the inner piston 24 toward the cylinder head 15 will start when thepressure reaches 1 pound per square inch and the outer piston 20 willstart to move in the same direction when the pressure reaches 1 /2pounds per square inch.

Assuming that the outer and inner pistons are in the position shown andthat the oil pressure starts to decline, when the pressure has declinedto 3 pounds per square inch, the inner piston starts to move toward thefirst cylinder head [4, but, as the outer piston 26 cannot move to theleft until the pressure declines further to 2 pounds per square inch,relative movement of the inner piston toward the cylinder head Ill andwith respect tothe outer piston takes place, with the result that, dueto separation of the peripheral edge or valve member '25 from theconical valve seat 2|, sudden drop in pressure in the chamber 43 andescape of oil therefrom occur and render the two springs effective tomove both pistons 2H and 24 and the rod I?! in the direction of thecylinder head 54, the rod moving toward the lever or element is and thelast portion of its motion in that direction being utilized to imparttripping movement to the latter.

Assuming that the pistons 2i? and 2d have moved to their extremepositions toward the cylinder head M, this movement being limited by theabutment end 32 of the sleeve is engaging with the shoulder (iii and theconical valve seat 2| of the outer annular piston 26 engaging theperipheral edge 25, and that the fluid pressure starts to build up inthe chamber #13, when the pressure reaches 1 pound per square inch, theinner piston 24 starts to move toward the right or toward the cylinderhead 55; however, as the outer piston 2i] cannot be moved by thepressure until a higher value, for example, 1 pounds per square inch isreached, both pistons move together, as the pressure increases, untilthe parts are in the initial position shown.

As hereinbefore pointed out, the shoulder 38 and the end 32 of thesleeve 26 limitmovement of the pistons toward the left or toward thecylinder head M, the peripheral edge 25 and the valve seat 3|cooperating to limit such movement of the outer piston 29 in thatdirection. Movement of the pistons toward the right or toward thecylinder head is limited by means of the flange face 23 engaging theradial abutment face [8, the valve seat 2! cooperating with theperipheral edge 25 of the inner piston 24 to limit movement of the innerpiston in that direction.

Because it is desirable to use springs of standard sizes or scales, andas the same adjustment is made for both springs, I prefer to provide theouter piston with a differential feature so that, as the outer pistonreaches the position at which the flange face 23 engages the abutmentface IS, the pressure in the chamber 43 is effective to apply increasedforce to the outer piston, the larger piston area of the latter thenbeing effective, and so that, when the pressure declines to a value suchthat the outer piston may move away from the abutment face I8, just assoon as separation starts, the effective area of the outer piston 21'!is reduced to its lower value, with the result that, without furtherdecline in pressure, the force of pressure acting on the piston islessened to the extent of decrease in piston area. Thus, as the outerpiston 20 engages the abutment face 18, the force of fluid. pressureacting on the outer piston is suddenly increased as the larger areathereof becomes effective, and, when movement of the outer piston awayfrom the abutment face l8 starts, the force of fiuid pressure issuddenly decreased because the smaller piston area then becomeseffective. In other words, there is provided a force differential actingon the outer piston and tending to hold the latter seated through amargin of pressure change depending upon the piston area change; andthis makes it unnecessary to complicate the springs by having the latteror scales correspond exactly to desired pressure conditions or by theprovision of means for effecting relative adjustment thereof.

While the invention has been shown in but one form, it will be obviousto those skilled in the art that it is not so limited, but issusceptible of various changes and modifications without departing fromthe spirit thereof, and it is desired, therefore, that only suchlimitations shall be placed thereupon as are specifically set forth inappended claims.

What is claimed is:

1. The combination with an element to be moved, of mechanism including arod having a range of axial movement and 50 disposed in relation to saidelement that movement of the rod in one direction is utilized to impartmovement to the element; said mechanism comprising a cylinder coaxialwith said rod; said cylinder having a head provided with an openingthrough which said rod extends; an annular outer piston fitting thecylinder, having an annular piston. area facing the head, and providedwith an annular valve seat disposed adjacent to its inner periphery andfacing the head; an inner piston having its piston area facing the headand having a peripheral edge providing a valve member for cooperationwith said annular seat and being movable from the latter toward the headwhen the inner piston moves relatively to the outer piston toward thehead; means providing for attachment of the inner piston to said rod; afirst spring for resisting movement of the outer piston toward thesecond head; a second spring for resisting movement of the inner pistontoward the second head; the scal of the second spring being greater thanthat of the first spring; a first cylinder abutment for limitingmovement of the outer piston away from said head; a second cylinderabutment for limiting movement of the inner piston toward the head; saidouter piston valve seat and said inner piston valve member cooperatingto limit movement of the inner piston away from the head when the outerpiston engages the first abutment and to limit movement of the outerpiston toward the head when the inner piston engages the second cylinderabutment; the piston areas of the inner and outer pistons cooperatingwith the cylinder and its head to define a pressure chamber; saidcylinder having a drain opening which is open to the spring spacethereof in all positions of the pistons; and means including a passagefor conducting to the pressure chamber fluid whose pressure may vary.

2. The combination as claimed in claim. 1 with a seat engaging the firstand second springs and adjustable axially of the cylinder.

3. The combination with an element to be moved, of mechanism including arod having a range of axial movement and so disposed in relation to saidelement that movement of the rod in one direction is utilized to impartmovement to the element; said mechanism comprising a cylinder coaxialwith said rod; said cylinder having a head provided with an openingthrough which said rod extends; an annular outer piston fitting thecylinder, having an annular piston area facing the first head, andprovided with an annular valve seat disposed adjacent to its innerperiphery and facing toward the head; an inner piston having its pistonarea facing the head and having a peripheral edge providing a valvemember for cooperation with said annular seat and being movable awayfrom the latter toward the head when the inner piston moves relativelyto the outer piston toward the head; means providing for attachment ofthe inner piston to said rod; a first helical spring having one endengaging the outer piston and serving to resist movement of the lattertoward the second head; a second helical spring disposed within thefirst spring and having one end engaging the inner piston to resistmovement of thelatter toward the second head; the scale of the secondspring being greater than that of the first spring; a seat engaging theends of the first and second springs remote from the outer and innerpistons; means for adjusting the seat axially of the cylinder; a firstcylinder abutment for limiting movement of the outer piston away fromthe head; a, second cylinder abutment for limiting movement of the innerpiston toward the head; said outer piston annular valve seat and saidinner piston valve member cooperating to limit movement of the innerpiston away from the head when the outer piston engages the firstabutment and to limit movement of the outer piston toward the head whenthe inner piston engages the second cylinder abutment; the piston areasof the inner and outer pistons cooperating with the cylinder and itshead to define a pressure chamber; said cylinder having a drain openingwhich is open to the spring space thereof in all positions of thepistons; and means including a passage for conducting to the pressurechamber fluid whose pressure may vary.

4. The combination with an element to be moved, of mechanism including arod having a range of axial movement and so disposed in relation to saidelement that movement of the rod in one direction is utilized to impartmovement to the element; said mechanism comprising a cylinder coaxialwith said rod; said cylinder having a head provided with an openingthrough which said rod extends; said cylinder having bores of larger andsmaller diameter joined by a radial abutment face; said bore of smallerdiameter extending from the radial abutment face away from said head andsaid bore of larger diameter extending from the abutment face toward thehead; an outer annular piston fitting the bore of smaller diameter,having an annular piston area facing the head, provided with an annularvalve seat at its inner periphery and facing said head, and having aflange disposed in the bore of larger diameter and the flange beingprovided with a radial face for engagement with said abutment face; aninner piston having its piston area facing the head and having aperipheral edge providing a valve member for cooperation with saidannular valve seat and being movable away from the latter toward thehead when the inner piston moves relatively to the outer piston towardthe head; means providing for attachment of the inner piston to saidrod; a first spring for resisting movement of the outer piston away fromthe head; a second spring for resisting movement of the inner pistonaway from the head; the scale of the second spring being greater thanthat of the first spring; means for limiting movements of the outerannular piston away from the head and of the inner piston toward thehead and comprising said radial faces of said abutment and of saidflange and an abutment carried by the cylinder for contact by the innerpiston; said outer piston annular valve seat and said inner piston valvemember cooperating to limit movement of the inner piston away from thehead when the radial face of the flange of the outer piston engages theradial abutment face of the cylinder and to limit movement of the outerpiston toward the head when the inner piston engages its abutmentcarried by the cylinder; the piston areas of the inner and outer pistonscooperating with the cylinder and its head to define a pressure chamber;said cylinder having a drain opening which is open to the spring spacethereof in all positions of the pis tons; and means including a passagefor conducting to the pressure chamber fluid whose pressure may vary.

5. The combination as claimed in claim 4 with common means for adjustingthe first and second springs to vary the forces exerted therebyon theouter and inner pistons. I

6, The combination with an element to b moved, of mechanism including arod having a range of axial movement and so disposed in relation to saidelement that the outer portion of movement of the rod in one directionis utilized to impart movement to the element; said mechanism comprisinga cylinder coaxial with said rod; said cylinder having first and secondheads with the first head located nearer to the element than the secondhead and the first head having an opening through which said rodextends; said cylinder having bores of larger and smaller diameterjoined by a radial abutment face; said bore of smaller diameterextending from the abutment face toward the second head and said bore oflarger diameter extending from the abutment face toward the first head;an outer annular piston fitting the bore of smaller diameter, having anannular piston area facing the first head, provided with an annularvalve seat at its inner periphery and facing said first head, and havinga flange disposed in the bore of larger diameter and provided with aradial face for engagement with said abutment face; an inner pistonhaving its piston area facing the first head and having a peripheraledge providing a valve member for cooperation with said annular valveseat and being movable away from the latter toward the first head whenthe inner piston moves relatively to the outer piston toward the firsthead; means providing for attachment of the inner piston to said rod; aspring seat in the cylinder and located adjacent to said second head; afirst helical spring interposed between the outer annular piston and thespring seat; a second helical spring interposed between the inner pistonand the spring seat; means carried by the second head for adjusting thespring seat axially of the cylinder; the scale of the second springbeing larger than that of the first spring; means for limiting movementsof the outer annular piston toward the second head and the inner pistontoward the first head and comprising said radial first head to define apressure chamber; said cylinder having a drain opening which is open tothe spring space thereof in all positions of the pistons; and meansincluding a passage for conducting fluid whose pressure may vary to thepressure chamber.

MANIOUS GOTTLIEB.

